Automatic position control apparatus



Oct. 17, 1950 E. w. PAESSLER 2,526,152

AUTOMATIC POSITION CONTROL APPARATUS Filed July 28, 1944 I Y 5 Sheets-Sheet 1 INVEI VTOR. f/P/C M4 P459515? 5 AGENT Oct. 17, 195 0 w, ss 2,526,152

AUTOMATIC POSITION CONTROL APPARATUS Fiied m 38, 1944 5 Sheets-Sheet s AGE/V T Oct. 17, 1950 Filed July 28, 1944 r E. w. PAESSLER 2,526,152

AUTOMATIC POSITION CONTROL APPARATUS 5 Sheet s-She'et 4 INVENTOR. f/P/C m P4555155 Patented Oct. 17, 1950 UNITEDY'STATESV PATENT OFFICE AUTOMATIC POSITION CONTROL APPARATUS Eric W. Paesslen Hackensack, N. J., assignor to Federal Telephone and Radio Corporation, New York, N. Y., .a.corporation of Delaware Application Jul'y'28, 1944, Serial No. 547,058

r 1 This invention relates to control apparatus and in particular to. mechanisms adapted to automatically tune. a radio transmitter or receiver to a predetermined frequency.

Many types of automatic tuning and control mechanisms have been developed. In .general the mechanisms have been used for controlling all possible settings of apparatus which requirea movement of 360 or less, e. g. condensers. On the other hand, the apparatus of my'invention is capable of adjusting. a control shaft of a circuit element through any. number of. degrees depend ing: upon the design of the apparatus and-the requirements to be met. For example, it is frequently desirable to vary the inductance of a multi-turn single layer coil by the continuous: rotation of a shaft on which is mounted'a roller,

or grooved pulley, the. latter makingcontinuous contact with theturns of the coil as it rotates.

Variable condensers of'the type wherein 'two col'lcentric cylindrical electrodes move -longitudi-' nally, one with respect to the other, may-also be adjusted by my apparatus. Similarly, induct- :ances employingxpermeabilitytuning may also be adjusted. Many otherapplicati'ons of my inven tion willv occur" to: thosensk-illed in the art, but my invention-'vzill. be described as. it :relatesto the" tuning of electrical circuits.

Among the objects'and features of my inventiona-re the following.

1. To providea; mechanism for automatically changing the constantsioi'an electrical circuit to" any one of a number of. predetermined values.

2. To provide a mechanism for producing a automatic position rotation. of any predetermined number of de rees as, for' example; when1varying -the tuningof an electrical circuit 'element from one value to another.

3. To providea. mechanism for automatically selecting. that direction of rotationv of a shaft which will most rapidly produce a desired result:

4. To provide a-mechanismwhich may be adjusted to a plurality of predetcrminedFsettings byavery-simple means.

Other objects and-features ofmyinvention will become apparent. as I pr'oceed with the specifications. i

In accordance with my-invention twoshafts are rotated at different fixed relative rates. The shafts mount a plurality ofpai'rs of'cams,"one

pair for eachdesired setting of the apparatus to be controlled. A separate detent mechanism is associated with each-pair. of earns. For any given operatien. the detent mechanism assooiated with- 8 Claims. (01492-142) the first shaft of the pair of shafts is held inoperative until the second shaft of said pair has rotated to a predetermined position. The selectivedetent mechanism associated with the second shaft then operates. to place the detent mechanism of the first shaft in an operative condition. During the following rotation of the first shaft its. associated detent mechanism operates to stop its rotation. The details by'Whlch: these operations are performed are illustrated in the accompanying drawings wherein Figs. 1 and. 2 illustratean endand a sideelevation, respectively, of the apparatus of my invention whereon are indicated the, planes from which. certain illustrative sections of the apparatus. are.

viewed.

Fig. 3 is a sectional view of the apparatus taken from the planei3.3.ofFig. 2.

Fig. 4 is a sectional. view of Fig. 2-taken from theplane t4. r Fig. 5 is another sectional view of Fig. 2 taken from the section 5.5.

Fig. 6 is a top view of in Fig. l and taken from planet-4i.

Fig.7 is a sectional view. of my apparatus as taken from the plane l-lin Fig. 1. V I Fig. 8 is aside elevation taken: from the plane 8-8 of Fig. l.

Fig.9 is an .end elevation 9-9 of Fig. 2.

taken from plane Fig. 10 is a view of certain detent-elements of the control mechanism at a selected timein its:

operation.

Fig. 11 is a schematic circuit diagram showing the interconnection of: certain magnets, relays;

switches; ctc., required for the operation of. my invention. The mechanical disposition of. these units is illustrated in the-various sectional views.

Referring to the figures, thetwo rotating shafts mentioned above" are represented -by reference The shaft I" is the one: to which a mechanical linkage, not shown, is con-- nested-for .in' turn varying the constant of; an electrical circuit element to a predetermined This shaft lrotates at" a considerably characters 1 and 2.

value. higher: speed than doesshaft 2, to which it' i's' connected by gearing as hereinafter-described, the rotation of shaft 2' andthe devices mounted thereon being employed to control the motion of shaft I whereby the latter will cease rotation aftera predetermined number of degrees. Both shafts are j'ournaled in end plates, or frame members, 3 and l. The frame members are spaced and rigidly held together by a plurality of spacing reds illustrated in cross section in Fig. e

the apparatuses shown by reference characters 5, 6, '7 and 8. The spacing members I and 8 are made of square cross sectional material in order to facilitate the mounting of certain parts on the flat sides thereof. The end plates are held to the spacing members by nuts and screws 9, I9, II and I2 as illustrated in Fig. 1 which shows an elevational' view of end plate 4. End plate 3 is held tothe spacers by similar means.

Referring particularly to Fig. 7 there is mounted upon shaft I a plurality of cams I3, the cams being spaced apart along the shaft by stepped spacers I4. It will be noticed that the cams do not bear upon the shaft directly but on the smaller diameter of the stepped spacers whereon they are free to rotate when not in a clamped position. In order to clamp the cams and spacers to shaft I and thereby form essentially a unitary structure, a gear I5 with an integral hub is pinned to the shaft at one end thereof. At the other end of the shaft a wing nut I6 applies pressure through the hub of hand knob I? to a washer I8 thereby clamping the cams and spacers against the hub of gear I5. All of the spacers I4 and the knob I! are prevented from rotating relative to the shaft I by the key or feather I9.

On the periphery or cam surface of each cam there is provided a notch 20. The relative location of this notch with respect to a fixed radius of the shaft determines in part the ultimate amount of rotation which the shaft makes in arriving at the final predetermined position of the tuning element as will be hereinafter described.

On shaft 2 a number of cams 2| and stepped separators 22 are mounted in a manner similar to that described in connection with shaft I. A collar 23 is pinned to one end of shaft 2 and a split collar 24 is clamped by screw 25 to the other end of the shaft. A spring washer 25 is positioned between the clamp 24 and the end cam to provide a certain amount of frictionbetween the cams 2| and the separators 22. This friction should be suflicient to effectively restrain any relative motion of the cams during normal operationbut not so great as to prevent their motion when sufficient pressure is applied during preliminary adjustment of the apparatus. Longitudinal motion of the shaft 2 is prevented by the radial and thrust bearing 27 positioned between end plate 4 and the dial 28, the dial being fastened to the end of the shaft b screw 23.

Mounted on collar 23 is a gear 30. As shown more clearly in Figs. 4 and 5, this gear mates with a pinion 3| mounted together with gear 32 on stub shaft 33. The stub shaft may be fastened to the end plate 3 by turning a shoulder on the shaft and passing the reduced shaft portion through a hole in the end plate 3 and fastening by a nut 34, see Fig. 8. Gear 32 mates with the pinion I5 mounted on shaft I. This gear linkage between shafts I and 2 maintains a constant relative rotational speed between the two shafts and in the illustrated embodiment of my invention is such that shaft I makes 24 revolutions to one revolution of shaft 2.

A motor drive 35 together with reducing gears is shown in Fig. 3. Pinion 35 connected to the motor shaft drives gear 31 which, together with pinion 38, is mounted on a stub shaft fastened to bracket 39. the latter serving to mount the motor on the end plate 4. The bracket is fastened to the frame by means of screws 40, 4! and 42. Pinion 38. drives gear 43 which in turn drives 4 the shaft I through a slipping clutch mechanism as follows.

Referring to Fig. 8 a shaft 44 is journaled in end plates 3 and 4. Rigidly mounted on the shaft 44 by set screws are a clutch plate 45 and a collar 46. Rotatably mounted on shaft 44 is the aforementioned gear 43. A thrust bearing is positioned on shaft 44 between end plate 4 and the hub of gear 43. At the other end of the shaft 44 a compression spring 41 loosely mounted over the shaft bears at one end against the collar 46 and at the other end against a second thrust bearing 48, the latter in turn bearing against end plate 3. The compressive force exerted by spring 41 may be suitably adjusted by fastening collar 46 at the proper point along shaft 44. A friction disc 49, composed of a suitable material such as cork, is positioned between the face of gear 43 and the clutch plate 45. It will be observed that the compression spring 4'! forces the clutch plate 45 against the gear 43 through the medium of the friction disc and the shaft 44 may thus be driven by the gear. During the operation of the control apparatus, shaft I becomes locked in a, given predetermined position and this in turn stops the rotation of shaft 44. However, due to the friction disc 49 gear 43 will continue to rotate for a short period of time. This continued rotation prevents unduly heavy loads being placed on the gears and their shafts as is well understood.

Pinion 50 is fastened to an extension of shaft 44 by suitable means such as, for example, a taper pin passing through the hub of the pinion and the shaft. Pinion 50 in turn. drives the shaft I through the gear 5I. The gear 5| may be mounted on the shaft by suitable means such as a set screw.

Referring to Figs. 3 and 4 the angular position of notch 20 of cam I3 relative to any fixed reference radius of shaft I determines the point where the shaft is stopped from rotating. Actual stoppage occurs when the detent 52 drops into notch 20 as the result of the operation of the detenting mechanism.

On shaft 53 is mounted a plurality of detent arms 54. 'These arms are free to rotate onshaft 53 under the control of certain latches, stops, and; tension springs; mounted thereon two spaced lugs 52 and 55 and an extension 56 on the opposite side of the shaft 53 from the spaced lugs. The extension 53 is in operative relation with a latch 51. The latch 51 is pivoted on shaft 58 and is under the control of one of a plurality of electro-magnets 59 or G0. The electro-magnet, when energized, attracts the armature BI, the latter being integral with latch 51. When the electro-magnet is de-energized the latch is normally held against a stop or rod 62 by the tension spring 63.

In the interest of economy of space the electro-magnets are divided into two banks, that bank comprising electro-magnets 59 being mounted on the spacing member I and the bank comprising electro-magnets being mounted on the spacing member 8. Alternate latches, all of which are mounted on shaft 58, are in cooperative relation with the electro-magnets of a single bank. This construction is clearly shown in Fig. 2. Referring again to Fig. 4 the L-shaped members 64 and 65, which form the individual return magnetic paths for the electro-magnets 59 and 63 respectively, have slots cut therein and the latches 51 are mounted so as to fit into these slots, thus preventing longitudinal motion along the shaft 58. To further assist in the prevention Each detent arm 54 has I of said longitudinal. motion; a. comb .66:.is-.mounted on spacin member 1, the; latches 5.1. being; constrainedzto move. in the spaces between. the teeth of; the. comb.

wAs-best illustrated on; Figs. 3., 4', and 5 there is shown. mechanism for; placing all of the detent arms. in an-ofi'orinoperative position where they are. held; by thelatches 51 bearing against ex-. I

tension. .56. .aflhisgmechanism comprises a lever 51 which is rigidly fastened to gear 68, the latter being freev tomo e on shaft 53. Gear 68 meshes. with a sector. gear; 69. mounted onshaft it. The shaft Til extends. acrossthe frame of the apparatus and isjournaled in frame members Sand 5. 'The lever and: gears just described are positioned immediatelywithin the frame adjacent the frame member 3': Immediately within. the frame-meme bet-4 is a second sectorgear'll which meshes with gear 1.2. 'Rigidly connectedwith gear 12 is a lever 1 3. Between levers'tl and-l3 is a reset shaft 14",:which is always constrained by tension spring 15 to bear againstat least. one of the detent arms 541.- An extension 16. of lever 13 permitsmanually resetting all of the detent levers totheir offxposition. For automatic operation, an arm 11 ofthe leverfi'l; extends to aposition where it may engage with a pin is extending from the armature 19 of a release magnetflll;

There is also insulatingly mounted on levertl a :pair of electrically connected spring contact members 31 and 8.2, see Fig. 5. :Member 3| carries: alcontact. which slides along contact strip 83 making a continuous electrical contact therewith. Member'BZ carries a contact which slides K oven the" surface of a plurality ofcontacts 84, .85, 86 andBJmountedon the terminal board 88. The members 8| and82 and; the contacts on the terminal board 8,8'make up the control switch shown on. the wiring diagram of Fig, 11-. The function of this switch and its operation-will be explained hereinafter. 1

- Referring to Figsr3 and 4 the operation of lug 55 f detent arm 54 together with cooperating cam..2|"wi1l now be explained. It will be seen thatthccam 2| comprises two sectors, each slightly less than 180. The cam surface 89 of one sector has a smaller radius than the cam mirface till. of the second sector. Between the sectors there. is; a notch 9| which is considerably widenthanthe notch 20 in the cam IS, the latter being'mounted, on the shaft I. Between the notch. 9| and the cam surface 95 there is a sloping surface. 92; This sloping surface serves to reverse the direction of rotation of the cam under certain operating conditions;

rReferring to Fig. 3 let it be assumed that the electro-magnet 59 attracts armature thereby The closing-of contacts 82:86 result inthe cnergization of .the driving motor fiend cams |3and 2| begin a counter-clockwise rotation in the direction of the. arrowabove stated cam I3 makes 24 revolutions to one revolution of cam 2|. During this period the notch 20 may pass several times be a e 11g .HQW- ever, this lug, cannot drop into the notch since it is restrained from doing so by the 111g 55 disengaging latch 51 from extension arm 55, thus permittingthe detent arm 54 to be pulledto the right. under the action of tension spring 93'. The motion of the detent arm- 54' is arrested when lug 55 makes contact with the cam surface 89. The

motion of detent arm 54 carries with it the reset positions that said lug may take on thevarious surfaces of cam 89 is such as to. make it expedient'to make contact 56 as'shown. The same construction is'also employed for the idle or off bearing on the cam surface 89;. The motion of the, lug- 55 toward: the surface 89 is such that the, lug 52 almost,,but not quite, makes contact withthe surface of cam |-3;. Cam 2| continues to rotate until'the leading edge of notch 9| becomes aligned with the edge of the lug 55.. At this moment lug 55 drops a'lirnited distance. into the notch 9| and lug 52 then rides directly upon the surface of cam I3. This condition is illustrated in Fig. 10. During the, time that the lug .55 passes from theleading edge to. the fol-. lowing edge of. notch-9| cam. l3 may make one complete revolution; However, during this, period the notch 25 will again pass the lug-15.2 at which time the lug falls, into the notch, :andshaft |.is arrested. .When lug 52 engages notch 20 detent arm. 54 and contact-member 82 move further to the right until the contact with Contact .186 is broken. There-is then no further action of, the apparatus-except theslowing down of the motor by the, friction disc ashereinbefore explained.

' Now let. us assume that at the beginning of any;sequence'of operationthe motion of lug 55 is arrested by the cam surface 95 of the cam 2|. Under these conditions it is clear that the detent arm 54 together with contact member 82 does notmoue as far to the right as in the former case. ,Arm 82,.makes contact with contact 85 under these conditions, resulting in the motor rotating shafts and 2 together with their respective cams in a clockwise direction. ,During a clockwise rotation the lug 55, after passing over the cam surface 95, rides down the sloping edge ;92 into the notch 9|. At this time the lug 52 again rides upon the surface of cam l3 and during the next revolution of the latter the notch 20 passes under the lug and the mechanism is arrested as before.

It will be seen. that conditions may arise wherein the operation of the mechanism may be initiated at a time when the notch 9| is such that the lug 55 falls into it directly. Insofar as the direction of rotation of the cams is concerned this is equivalent to a counterclockwise rotation since the contact member 82 will. come to rest on contact 86. Inasmuch as not more than one revolution of cam l3 takes place while the'lug 55 is within notch 9|, it is apparentgthat thedesired direction of rotation becomes critical at this point. If the center of 1ug-"55islto the left of the center of notch 9| when the lug 55 enters the notch, conditions are such that lug. 52 will fall within notch 25 of cam |3 sometime during the nextrevolution of the latter cam. On the other hand if the center'of lug 55 is to the right of the center of notch 9|, theposition of notch 20 is-such that during its rotation it has already passed the point. where it will engage lug 52 during the period when lug 55 is within notch 9|.- Under these Zconditions; the rounded edge of'lug 55 rides up the sloping edge 92 until it reaches the surface 90. This pushes detent arm 54 and-con tact member 82 to theleft where the latter engagescontact- 55. This reverses the direction 7 of the driving motor and of the cams. The cams are now rotating in a clockwise direction and the lug 54 retraces its path along the sloping edge 92, falls into the notch 9| and, during its motion across the notch, lug 52 enters notch 29 and the cycle of operation is complete.

In order to accurately center lug 55 Within notch 9| a plurality of latch arms 94 is provided, one for cooperating with each detent arm 54. These latch arms are more clearly shown in Fig. 2. Each latch arm is tensioned by a spring 95 which tends to make the arm follow the movement of its cooperating detent arm. A lug 96, bent at right angles to the plane of the latch arm, engages the back edge of a cooperating detent arm. This lug arrests the motion of the latch arm so that a centering lug 91, also part of the latch arm, will not approach the cam surface and interfere with the operation of the mechanism. It will be seen that lugs 55 and 91 are symmetrically positioned about a center line. For accurately spacing lug 55 within the center of notch 9|, cam 2| is rotated until the lug 91 is permitted to fall within the notch. This is done manually when adjusting the apparatus. Since the width of lug 91 is such that it mates with the notch 9|, it will be seen that this condition can easily be obtained. It is also the condition, of course, wherein notch 20 will be engaged by lug 52.

The manner in which the control apparatus is adjusted so that it will automatically tune the inductor of a radio frequency circuit whereby said circuit will operate at any one of a plurality of predetermined frequencies will now be described.

It is assumed that the shaft is coupled to a shaft within a single layer inductor and on said latter shaft there is mounted a grooved pulley which makes continuous contact with the turns of the inductor as the shafts rotate. The mechanism by which the grooved pulley is mounted on the shaft within the inductor is such that the pulley will also move longitudinally along the coil. This is in accordance with well known practice and is therefore not illustrated. In the specific embodiment of my invention illustrated by the accompanying drawings, I have shown ten pairs of control cams, detent mechanisms, etc. This will permit the radio frequency circuit to be tuned to ten different frequencies. It is convenient to progressively tune the circuits. For example, the cam mechanism nearest the adjusting knob I! may be employed to tune the circuit to the lowest frequency, the next cam mechanism for the second lowest frequency, and so on to the tenth cam mechanism which will tune the circuit to the highest frequency.

Referring to Figs. 3 and 7, the extension handle 16 of lever '53 is pushed to the left thereby disengaging all of the detent arms 54. The wing nut it within the knob I? is loosened. This releases the clamping force applied to the cams |3. One of the detent arms, for example, that one closest the knob I? is released by manually raising the armature 6| of the corresponding latch 51. falls within notch 9| of cam 2| as above described. Lug 52 obviously falls within notch 2|) at this time. At this point the radio'frequency circuit will in general not be properly tuned. By'

Knob l! is rotated until centering lug 91' of cams under adjustment have not rotated since they are held from so doing by the lug 52. However, the remaining cams on both of the control shafts are rotating during all of the adjustment period. The tuning of the radio frequency circuit to the first frequency having been completed the handle 16 is again moved to the left and all detent arms are placed in the off position. The armature 6| of the next or adjacent latch to the one which has just been employed to initiate the first setting is now raised thereby releasing the second detent arm. The knob I! is turned until centering lug 91 of the second latch arm 94 engages the notch 9| and operation is continued in the same manner as with the first setting. After the second setting has been completed the same operation is continued until all of the cams and their associated detent mechanisms are properly adjusted for the desired predetermined frequencies. All of the cams associated with shaft l are now securely clamped in position by the wing nut l6 and the apparatus is ready for automatic operation which will now be described.

Fig. 11 is a schematic diagram showing the selector magnets, relays, control and selector switches, etc. for the automatic operation of my automatic control device. A ten position selector switch and a start key may be mounted in any convenient location. This switch and key are separate units from my control device but all of the other magnets, relays, etc. are illustrated in the various figures of the drawings.

The selector switch is set for a desired frequency to which the radio frequency circuit is to be tuned. say position 1, connected with one of the selector-magnets 59. The start key is momentarily depressed. This energizes the release magnet whose armature 19 is thereby attracted and contacts 98 open and contacts 99 close. At the same time the mechanical linkage between armature 19 and the contact members 8| and 82 urges the latter to the extreme left of their travel. The closing of contacts 99 completes a circuit from ground, a battery or power source,

" the winding of the selector magnet 59, through position I of the selector switch, contacts 99, contacts I99, to ground. The operation of the selector magnet 59 releases the cooperating detent arm 54 which as above described moves to the right until lug 55 comes to rest on a cam surface, let us assume surface 89 of cam 2|. This is the low surface of the cam. As a result of this motion the contact arm 82 of the control switch comes to rest on contact 86. It is understood that this latter motion of the contact arm 82 can only occur when the start key is released and the relay magnet 89 is de-energized thus permitting the armature 19 to be returned to its original position through the agency of the tension spring IBI. Reclosing of contacts 99 completes a circuit from ground through battery or power source 192, relay I93, contacts H14, con tacts 86 and 82, the sliding contact between contact arm 8| and the bar 83, contacts 98, contacts 189, to ground. The operation of relay I03 closes contacts I05, the latter functioning as holding contacts for the selector magnet 59. The operation of relay I93 also closes contacts I96 and 101 and the motor operates so as to rotate the cams l3 and 2| in a counter-clockwise direcllll, the motor field coil, contacts I96, through the motor armature, to the other side of the A.-C.

I source. The motor operates until the lug 52 engages the notch of cam 3, at which time "the detent arm 54, which is mechanically interlinked with switch arm 82; moves the latter tothe right until'the contact betweencontacts'88 and the arm 8-2 is broken. This stopsthe motor as above de-' scribed and the cycle of operation is complete.

"If it should happen that the lug of detent arm '54 should come to rest on the cam surface of cam 2|, the following action takes place. It will be observed that the surface as is the high surface of the cam and therefore con-tact arms 8| and 82 come to rest so that the latter makes contact with contact 85. Y The closing of this latter contact energizes the relay Hit through a circuit from ground, battery #09, the winding of relay I08, contacts '85 and 82, the contact between arm 81 and the bar 83, contacts '98, contacts Hill, to ground. The closing of relay I08'closes contacts H0 which act as a holding contact for the selector magnet. of relay I08 also opens contacts 1-134 and closes contacts Ill, H2 'and'llt which in turn close a circuit throughthe motor in a manner such that thelatter rotates in a clockwise direction. The circuit through the motor may be traced from the volt A.--C. power source, contacts H3, the field coil of the motor, contacts 1 12, the motor armature, to the other side of the A.-C. source. The openin'g'of contacts I04 prevents relay I03 from becoming energized as long as :3.

relay I08 remains closed. Also, the closing of contacts HI places the contacts 85- and 86 of the control switch in parallel. Therefore, as contact'arm 82 moves between contacts 85 and 35,

there is no interruption of the circuit which en ergizes relay [08. The operation of contacts I04 and l H thus prevents a reversal in the d rection of rotation of the motor as the lug 55 travels down over the sloping surface 92 to a position which would normally cause the motor to operate the cams in a counter-clockwise direction. The motor operates until the detenting action has taken place and the cycleis completed.

If the lug 55 of the locating arm 54 should fall within the notch 9| in such a position-that it is on the right hand side of the notch the following action takes place. Relay Hi3 .ener gizes and the motor operates torotate the cams in a counter-clockwise direction since the .arm 82 makes contact with contact 86. The rotation of cam 2.! causes the lug 55 to travel over the sloping surface 92 .until it reaches the surf-ace 90. This action breaks the contact between arm 82 and the contact 8.6 and makes contact between the arm v8-2 and cont-act 85. Belay its becomes energized and opens contact Hi4 thereby releasing relay N33, The energizing of relay 108 causes the motor to operate so asto rotate the cams in a clockwise direction. This rotation continues until the detenting action has taken place and the cycle of operation is complete. v

' In the above descriptionQ-the contours of the cam surfaces have been described as having notches which, with certain cooperating lugs, comprise the detent mechanisms. Othercam contours for the detenting devices could also be employed, e. g., the cams could have lugs in place of notches on their periphery andthe l-ugs could engage with suitable notches on the detentarms.

The closing ends of the inductor under adjustment. Re-

mounted on the end of shaft 4. A lever i i-6 is pivoted on the shaft H1. I Two pins 'H-B and H9 are positioned on the lever I It as illustrated.

So far I have not described a safety switch which prevents the control apparatus rotat ng the above mentioned grooved pulley beyond the;

Pin H8 is constrained to ride over the surface of cam H4 by a tension spring connected to lever H6. Mounted on the end frame 3- is a pair of contacts Hi0, these contacts being operated by an insulating bar 125 mounted on the lever H6. It will be recalled that shaft 1 makes 24 revolutions for one rotation of shaft 2. How'- ever, one of the objects of my invention is to devise an apparatus which will operate in a minimum time and, therefore, any cam 21 on shaft I will never make more than a rotation since a lug 55 always moves toward-the notch 91 over the shortest route. In effect this is equivalent to limiting the maximum number of rotations of shaft i to one-half of '24 or 12..

Due to practical expediencies, such as the relative wide width of notch 9!, etc., the actual number' of rotations of shaft l is preferably limited to ten. In the present instance this means that the maximum number of turns 'over which an inductor may be adjusted is ten.

I The cam H4 also has a high and a low sector and the high sector permits a maximum'number of ten revolutions of shaft I before the safety switch operates to disconnect the power supply. Bothelectrical and mechanical safety'is provided. 7 When the pin HB rides on the low surface of cam H4, contacts 1-00 are open and the apparatus cannot function. Likewise, the engage ment of lug l2] of stop disc H5 with pin 1E9 prevents the further rotation of shaft'fll. When the pin H8 rides on the high surface of cam H4 lever H6 is pushed to the right thereby clos ing contacts I00 and the apparatus will operate in the desired manner. the riding of pin H8 on .the high side of cam H4 also prevents any engagement between the pin H9 and the stop I21. In Fig. 9 the posif tion of the safety switch is shown just after the shaft has reached one extreme of its travel- The pin H8 has just moved from the high to the low sector of cam H4 and lug IZI has ,justflengaged pin vl I9;

My invention has been described primarily as a mechanism for automatically tuning radiofrequency circuits to predetermined frequencies. It is obvious, however, that the apparatus could also housed in any arrangement wherein'a pre-.

determined setting .of any movable part is requiredand it is intended that the scope of my inventiontbe not limited except in accordance withthe following claims. 1

What 'is claimed is: I

1. Rotary position determining control apparatus comprising a plurality of control shafts, a plurality of sets of cams mounted in predetermined relative position on said shafts, ,on cam of each set of cams being mounted on a separate shaft of saidplurality of shafts, means for rotating said shafts at different relative speeds, means for selecting the direction of rotation of said I shafts, a notch on the camsurfaces of each cam of each set of cams, a given inclined portion on one of said earns, a detent cooperating with said inclined portion to determine direction of-shaf-t rotation a plurality of detent means, one for each set of cams, each detent means being posit oned and operative for potential engagement 75 th 6 notches on one set of cams, selector It will be observed that means for initiating the operation of at least one of said detent means so that when as a result of said rotation said notches are in a predetermined relative position with respect to said one of said detent means said engagement takes place, and means for stopping the rotation of said shafts in response to said engagement.

2. Rotary position determining control apparatus in accordance with claim 1 wherein said detent means comprises a plurality of detent arms, two spaced lugs on each arm for engagement with said notches, the notch on the cam surface of one cam of One pair of cams being wider than the width of its cooperating lug, whereby, during the engagement of said last mentioned notch and lug, the notch in the other cam of said pair of cams makes one complete revolution.

3. Rotary position determining control apparatus in accordance with claim 1 in combination with means for placing a l of the detent means in an inoperative position prior to the operation of a selected one of said detent means.

4. Rotary position determining control apparatus comprising a first shaft adapted for a rapid rotation, a second shaft adapted for a slower rotation than said first shaft, means for rotating said shafts at fixed relative rates, a plurality of cams adjustably mounted on said first shaft, a like plurality of cams adiustably mounted on said second shaft, each of the cams on one shaft being in operative relation with a cam of the other shaft there y. forming operative pairs of cams, a notch on the cam surface of each cam of each pair of cams, a plurality of detent means, each detent means comprising a detent arm carrying two spaced lu s for engagement with the notches on one pair of cams when said notches are in a predetermined position relative to said lugs; means for determinin the direct'on of rotation of said shafts comprisin high and low arcuate segments on each cam of said second shaft, the notch in said each cam, and a s oping portion between the notch and said hi h segment, said last mention d notch being wider than its cooperating lug; and means for stopping the rotation of said shafts in response to an engagement between the two lu s of any detent arm and their cooperating notches.

5. Rotary position determining cont ol a paratus in accordance with claim 4 in comb nation with additiona means for adirstin each of said detents and their cooperating c ms to their predetermined positions for permitting said engagements.

6. Rotary position determining control apparatus in accordance with claim 4 in combination with means for adiusting each of sa d detents and their cooperating cams to their pr determined postions for rermittins s id en agements, said means comprising a plu a ity of lat h arms, one latch arm coop-eratin with one det nt arm, a centering lug on each latch arm. said centering lug enga ing a notch on a cooperating cam when the notch whi h is wider than its coo erating lug is in a predetermined position with respect to said last named lu o 7. Rotary posit on dete mining contro ap aratus comprising a plurality of control shafts, a plurality of sets of cams mount d in predetermined relati e position on said shafts. one cam of each set of cams being mounted on a separate shaft of said plurality of shafts, means for rotating said shafts at different relative speeds, means for' selecting the direction of rotation of said shafts, a notch on the cam surfaces of each cam of each set of cams, a plurality of detent means, one for each set of cams, each detent means being positioned and operative for potential engagement with th notches on one set of cams, selector means for initiating the operation of at least one of said detent means so that when as a result of said rotation said notches are in a predetermined relative position with respect to said one of said detent means said engagement takes place, means for stopping the rotation of said shafts in response to said engagement, said means for determining th direction of rotation of the control shafts comprising a plurality of cams, said plurality comprising one cam of each set of cams, said plurality of cams having irregular profile surfaces, and a plurality of locator means for riding over the surfaces of saidplurality of cams, one of said locator means being selected for operation by the selector means initiating the operation of one of the detent means.

8. Rotary position determining control apparatus comprising a plurality of control shafts,-a plurality of sets of cams mounted in predetermined relative position on said shafts, one cam of each set of cams being mounted on a separate shaft of said plurality of shafts, means for rotating said shafts at different relative speeds, means for selecting the direction of rotation of said shafts, a notch on the cam surfaces of each cam of each set of cams, a plurality of detent means, one for each set of cams, each detent means being positioned and operative for potential engagement with the notches on one set of cams, selector means for initiating the omration of at least one of said detent means so that when as a result of said rotation said notches are in a predetermined relative position with respect to said one of said detent means said engagement tak s place, means for stopping the rotationoof said shafts n response to said engagement, said means for determining the direction of rotation of the control shafts comprising a plurality of cams, said plurality comprising one cam of each set of cams each cam of said plurality of cams having an rregular profile surface including one of said notches, and a hi' h and a low arcuate s ment, and a s oping portion between said one of said not hes and said hi h arcuate se ment; and a pluraitv of locator means adapted to ride over the surfaces of said plurality of cams, one

of said locator means being selected for operation by the selector means initiating the operation of one of the detent means.

ERIC W. PAESSLER.

REFERENCES CITED The fo o ing references are of record in the file of this patent:

UNITED STATES PATENTS J Number Name Date 2,249,753 Elliott July 22, 1941 228 .414 Collins June 9, 1942 2,320, 67 Hill June 1, 1943 23343 24 Pa ssler Nov. 23, 1943 2,356,905 Zenner Aug. 29, 1944 2,391,470 May Dec. 25, 1945 

